sponge cake, once a special cake using only eggs, sugar, and flour baked in an attractive mold or shaped as a biscuit, is now encountered in tiramisù, Twinkies, and store-bought strawberry shortcake shells. Beating air into eggs for long periods, particularly when the eggs are separated, causes the whites to form a mountain of foam, forcing the batter to rise when heated, which results in a lighter texture than the centuries-old yeast, pound, and fruit cakes. See fruitcake and pound cake. Recent sponge cakes may contain oil, butter, and even baking powder.
